Fusible electric switch having means for pivotally supporting replaceable cartridge fuses on a tiltable carriage



Dec. 6, 1966 H. D. KURT 3,290,459

FUSIBLE ELECTRIC SWITCH HAVING MEANS FOR PIVOTALLY SUPPORTINGREPLACEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE Filed Dec. 22, 1964 5SheetsSheet 1 FIG./.

//v VENTOR. Ho WARD D. KURT,

ATTORNEY H. D. KURT Dec. 6, 1966 FUSIBLE ELECTRIC SWITCH HAVING MEANSFOR PIVOTALLY SUPPORTING REPLACEABLE CARTRIDGE FUSES ON A TILTABLECARRIAGE 5 Sheets-Sheet 2 Filed Dec. 22, 1964 INVENTOR. HOWARD 0. KURT,

B W ATTORNEY Dec; 6, 1966 H D. KURT 3,290,459

FUSIBLE ELECTRIC SWI'I CH HAVING MEANS FOR PIVOTALLY Filed Dec. 22, 1964SUPPORTING REPLAGEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE 5Sheets-Sheet 5 /NVENTOR.' HOWARD D. KURT,

ATTORNEY Dec. 6, 1966 H. D. KURT 3,290,459

FUSIBLE ELECTRIC SWITCH HAVING MEANS FOR PIVOTALLY SUPPORTINGREPLACEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE Filed Dec. 22, 1964 5Sheets-Sheet 4 /NVEN70/?.' Ho WARD 0. KURT,

A TTOR/VEY 3,290,459 ALLY H. D. KURT Dec. 6, 1966 FUSIBLE ELECTRICSWITCH HAVING MEANS FOR PIVOT SUPPORTING REPLACEABLE CARTRIDGE FUSES ONA TILTABLE CARRIAGE 5 Sheets-Sheet 5 Filed Dec. 22, 1964 /NVE/VTO/?HOWARD Z2 KURT, 5y QQJIMt S. mm ATTORNEY United States Patent Filed Dec.22, 1964, Ser. No. 420,267 8 Claims. (Cl. 200-50) This invention relatesto electric switches, and more particularly it relates to a switch inwhich contact means for switching an electric current circuit and fusemeans for protecting the circuit are integrally combined.

The present invention has special utility in relatively high current(e.g. 1200 amperes), 600-volt service entrance applications wheremultipole fused switches with bolted-pressure contacts are commonly usedto switch and to protect A.C. electric power circuits and loads fed fromservice entrance conductors. In practice such devices are equipped withlow-cost manually or electrically operated mechanisms for opening themain switch contacts when desired, thereby breaking the circuit in whichthe device is connected and interrupting whatever load current may thenbe flowing. Overload and fault protection is automatically provided bythe electric fuses which are designed to blow under overcurrentconditions with a time delay inversely related to overcurrent magnitude.By using Class L (NEMA standards designation) lowvoltagecurrent-limiting cartridge fuses, current as high as 200,000 amperes canbe quickly and safely interrupted in the event that a very severe faultor short circuit occurs.

Sometimes an overload or fault condition will preexist in the protectedcircuit when a service entrance switch is being closed. On realizingthis, an operator is likely to react by immediately attempting to reopenthe switch. If the fault current magnitude is sufliciently high, thefuses will interrupt it with dispatch before the operator can separatethe main contacts of the switch. But for complete protection, theseparable contacts of a service entrance switch should be designed tosafely interrupt the maximum amount of current (e.g. 6 times ratedfull-load current, or 7,200 amperes) that the fuses will let through,without blowing, for the minimum length of time required to carry out aswitch opening operation.

Heretofore it has been conventional practice in commercially availableservice entrance switches to mount the fuses in a relatively stationaryposition adjacent to the movable switch contacts, whereby in each poleof the switch the two electrical junctions formed at the respective fuseterminals are in series with the two electrical junctions interposed bythe switch contacts. High-current switches of such design generally havehad one or more of at leastthe following shortcomings: (l) Relativelylarge and bulky physical dimensions; (2) undesirable heat generation andcumulative power losses at the four separate, serially-connectedelectrical junctions; (3) relatively inconvenient arrangement of maincontacts and operating mechanism for installation and servicingpurposes; (4) dif ficult access to blown fuses for the purpose ofremoving and replacing the same; (5) lack of assurance that bothterminals of a blown fuse are deenergized prior to removing the fuse.

'In some prior art fusible switch designs, provisions have been made formounting a cartridge fuse in place of the movable blade of a switch.Such designs generally have not been suitable for multipole high-currentswitches. For service entrance applications in particular, they aresubject to some of the shortcomings enumerated above and, whereswitching and fuse-access functions have been combined in a singleoperation, still other shortcomings are potentially involved: (1) Highforces required to close 3,290,459 Patented Dec. 6, 1966 the switch; (2)hazard on opening the switch to an operator standing nearby; (3)relatively large space occupied by the switch when open.

Accordingly, a general object of the present invention is the provisionof an improved switch for high-current service entrance applications andthe like.

A more specific object of my invention is to provide means forfacilitating maintenance of a compact, multipole, fusible electriccircuit disconnecting device that is designed to avoid or to minimizethe above-mentioned shortcomings of the prior art.

Another object is to provide a relatively simple yet very safe andreliable switch of this kind in which a blown fuse is movable, afterfirst opening the switch contacts, to a special position where both ofits terminals are disconnected and the fuse is exposed for convenientremoval and replacement.

My invention contributes materially to the construction of a 3-pole,high-current fusible switch that is characterized, to an unusual degree,by compactness in size, safety and convenience in operation andmaintenance, and low cost in manufacture.

In carrying out my invention in one form, a compact, dead-front,high-current fusible switch is provided with a manual operating handleand a mechanism for safely closing or opening the switch withoutexertion of untoward force by the operator. The mechanism is connectedto a movable switch member the back side of which is adapted to supportone or more removable cartridge fuses. The switch member is pivotallymounted on a carriage that is pivotally mounted in turn on a stationarypart of the switch. Hence the carriage is disposed for reciprocalmovement between predetermined operating and tilted positions. Operationof the mechanism while the carriage is in its operating position causeseach fuse to be moved into or out of a closed circuit position in whichit bridges an associated pair of spaced-apart relatively stationarycontacts by directly engaging the same.

Whenever the switch is open, the carriage can be moved to its tiltedposition where a blown fuse will be exposed, in a completely deenergizedstate which is clearly visible to the operator, for safe and convenientremoval and replacement. Since both terminals of the fuse are thusdisconnected from the associated stationary contacts, either one ofthese contacts can be safely connected to the electric power source. Inone aspect of the invention interlocking means is provided to ensurethat the carriage is anchored in its operating position except when theswitch is open. In still another aspect of the invention, the carriageis made separable from the stationary part of the switch in its tiltedposition, thereby enhancing the ease with which the switch can beinitially installed and the convenience of subsequently servicing itsfuses, contacts, and operating mechanism.

. My invention will be better understood and its various objects andadvantages will be more fully appreciated from the following descriptiontaken in conjunction with the accompanying drawings in which:

FIG. 1 is a front elevation of a 3-pole electric switch embodying myinvention;

FIG. 2 is a side elevation of the FIG. 1 switch in an open circuitcondition, with portions of the front and the back frames of the switchbroken away to more clearly show its interior parts;

FIG. 3 is a partial front elevation of the switch shown in FIG; 2 afterthe front frame and its associated parts as well as the arc-quenchingmeans have been removed;

FIG. 4 is an enlarged side view of the movable bridgelike switch elementshown in FIG. 2 and of the means by which it is removably supported;

FIG. 5 is a side elevation similar to FIG. 2 but with the bridge-likeswitch element shown in its closed circuit position; and

FIG. 6 is a side elevation of the switch shown in FIG. 1 with the frontframe and associated switch elements tilted in accordance with myinvention to a disconnected position.

Referring to FIGS. 1 and 2, the illustrated switch will be seen toinclude a stationary unit 11, three pairs of spaced-apart incoming andoutgoing electric current conductors 30 and 40 fixedly supported by theunit 11 in side-by-side relation to each other, and a carriage 101adapted to support means for closing and opening a circuit between theseparate conductors forming each pair 30, 40. The carriage 101 alsocontains a mechanism for conjointly actuating all three of the circuitclosing and opening means, and this mechanism includes a manualoperating handle 120 that is accessible from the front side of thecarriage escutcheon 110. The handle 120 is pivotally movable between avertical, switch open position shown in solid lines in FIG. 1 and araised, switch closed position shown in broken lines.

The entire switch assembly is adapted to be mounted in any suitableenclosure having an openable front cover for access, with the unit 11being bolted or otherwise secured to the enclosure and the escutcheon110 and the handle 120 protruding through a conforming aperture providedin the cover. The operating handle 120 in its raised position wouldprevent opening of the cover, thereby blocking access to the interior ofthe enclosure so long as the switch is closed.

The constnuction of the stationary unit 11 of the switch will now bedescribed. The unit includes a back frame having generally L-shapedmetal side structures that are rigidly fastened together by a pluralityof cross pieces. As is best seen in FIG. 6, each of the side structurescomprises an angle disposed vertically to form a rear corner post 12 andbent horizontally to form a side member 13 extending frontwardly fromthe lower end of the post 12. At the front end of the member 13 arelatively short upstanding plate 14 is afiixed, and this plate isadditionally fastened to the midsection of the post 12 by means ofadiagonal brace 15. A notch 16, bounded by a horizontal upper lip 14aand a vertical lower lip 14b, is provided in the frontside of the plate14 for removably receiving and holding a support pin 116 of the carriage101.

At a point 17 on the' rear section of the side member 13 there ispivotally mounted an upstanding support and locking member 18. Thismember is spring biased to a position in which a corner 18a thereofbottoms on the horizontal flange of the side member 13 and in which ananchor pin 18]) carried by the member 18 is disposed directly above thecorner 18a as shown. The side member 13 is joined to the correspondingmember on the far side of the stationary unit by a bar 19 that extendsacross the bottom of the unit, and the two corner posts 12 are spannedat different elevations by two horizontal channels 20 and 21 that aretightly bolted to the backsides thereof. The channels 20 and 21 are madeof rigid, electrical inswlating material.

The stationary unit 11 also includes a plurality of separate pairs ofspaced-apart relatively stationary electric contacts 31 and 41, whichpairs are mounted in sideby-side relation to each other on theinsulating channels 20 and 21 of the frame described above. A front viewof one pair of contacts is shown in FIG. 3 (and the other pairs areessentially the same). It will there be seen that the contacts 31 and 41are of jaw-like design, that is, each one comprises a pair ofelectrically interconnected, physically spaced electroconductiveelements or contacts 32 and 33 arranged to grip opposite sides of amovable bladellike contact inserted in the gap therebetween. Thecontacts 32 and 33 preferably comprise defiectable silver plated copperbars having their flat sides in parallel vertical planes that areperpendicular to the channels 21 and 22 and having their forward edgesbeveled to guide the cooperating blade on its insertion therein.

Adjoining the outer side of the bar 32 of the lower stationary contact41 is a dished member 34 that is rigidly fastened to the associatedchannel 21. The bar 32 is affixed to this member. A depending portion ofthe bar 32 is connected to and supports the aforesaid conductor 40 in aconvenient disposition for connection to an external electric powercircuit, and a similar portion of the companion bar 33 is also attachedto the conductor 40. The bars 32 and 33 extend vertically from theconductor 40 in spaced parallel relation to each other, and anotherdished member 37 is located on the outer side of bar 33 opposite themember 34 as shown. At one point between the bars 32 and 33 a suitablespacer 38 is disposed for the purpose of maintaining between the innersides of the bars at this point a predetermined minimum gap whose lengthis approximately the same as the thickness of the blade to be inserted.

In order to ensure a tight yet separable connection between the bars 32and 33 and the blade that is inserted therebetween, suitable pressureapplying clamping means is provided. As shown in the drawings thisclamping means includes a common rotatable drive shaft 60 extendinghorizontally through aligned apertures in the respective bars 32, 33 andmembers 34, 37 that comprise each of the lower contacts 41. The shaft 60is insulated so that the separate contacts 41 will remain electricallyisolated from each other, and it is surrounded at each of these contactsby a pair of annular members 62 and 63.

.The annular member 63 is housed in the dished member 37, and preferablyit comprises a non rotatable nut having an internal screw thread. Theother member 62 preferably comprises an externally threaded tubular boltthat can be rotated with respect to the nut 63 by predetermined rotationof the shaft 60. The bolt head is located in the dished member 34, andthe bolt extends along the shaft 60 into the member 37 where it mateswith the nut 63. Thus the head of the bolt 62 and the nut 63respectively bear against opposite sides of the stationary jaw-likecontacts, and the cooperating blade like contact can be tightly clampedbetween the bars 32 and 33 by rotating the shaft 60 so as to turn thebolt into the nut. This bolted pressure arrangement Will be furtherdescribed hereinafter.

The construction of each upper contact 31 of the stationary unit 11 issimilar to that described above for the lower contact 41. However, thespaced bars 32 and 33 forming each of the jaw-like contacts 31 extendupwardly instead of downwardly from the associated members 34 and 37 tothe attached conductor 30, with each member 34 being rigidly fastened(by the means shown at 39 in FIG. 2) to the upper insulating channel 20instead of to the lower one.

It is now apparent that by electrically interconnecting the pairedcontacts 31 and 41, a closed electric circuit will be formed betweencorresponding upper and lower conductors 30 and 40, and for this purposea bridge-like electroconductive element 201 having blade-like maincontacts 201a and 2011) at opposite ends thereof is provided. Theelement 201, which is shown in phantom in FIG. 3, is supported in amanner hereinafter fully described by a movable switch member on theaforesaid carriage 101. When its contacts 201a and 20111 are insertedbetween the jaw-like contacts 32-33 of 31 and 41, the element 201completes a main current path between conductors 30 and 40.High-pressure, lowresistance connections between these cooperating maincontacts is then obtained by actuating the above-described clampingmeans.

The common drive shaft 60 of the clamping means associated with therespective upper contacts 31 and the corresponding drive shaft 60 belowhave been intercon nected for joint rotation by a pair of tie bars 64.The.

upper ends of the tie bars 64 are pivotally attached at 65a to a pair ofcranks 65 that are respectively keyed to opposite ends of the uppershaft; the lower ends of these bars are pivotally attached at 66a to apair of cranks 66 keyed to opposite ends of the lower shaft. Both of theshafts 60 are biased in a pressure relieving direction (counterclockwise as viewed in FIG. 2) by means of a pair of springs 67 each ofwhich is connected in tension between one of the tie bars 64 and theadjacent corner post 12 of the stationary unit so as to urge the barupwardly. Both shafts are simultaneously rotated in the opposite,pressure-applying direction by actuating means located on the carriage101, soon to be described.

Each of the upper relatively stationary contacts 31 also includes a pairof jaw-like arcing contacts 42 and 43. These arcing contacts compriseelongated, relatively thin metal members disposed between the bars 32and 33 adjacent to the main contact area thereof. The upper ends of themembers 42 and 43 are physically and electrically connected to thestationary bar 32 by a bolt 44 of other suitable means. The lowerportions of the members 42 and 43 are bent to protrude in front of thebar 32 (best seen in FIG. 5), where they form a relatively short gap inalignment with the gap between the bars 32 and 33 (best seen in FIG. 3).The tips 42a and 43a of the protruding portions of these members areturned up to form are runners.

The protruding portions of each pair of relatively stationary arcingcontacts 42 and 43 are arranged to be separably engaged by a blade-likearcing contact 202 that is mounted on the movable switch member of thecarriage 101 in association with the main contact 201a of each of thebridge-like elements 201. When the element 201 is in a closed circuitposition (FIG. 5), its arcing contact 202 is disposed between thecooperating arcing contacts 42 and 43 which yieldably grip oppositesides of the contact 202 to maintain a good electrical connectiontherewith. During movement of the element 201 toward an open circuitposition, the arcing contacts 202 and 42, 43 will not separate untilafter the main contacts 201a and 32, 33 are disengaged, whereupon anelectric arc may be drawn between the arcing contacts. Any such arc willbe contained and extinguished within an electric arc chute 50 thatembraces the protruding portions of each pair of the stationary arcingcontacts 42 and 43.

As is seen in FIGS. 1 and 2, a clamp 51 and a pair of long bolts 52 areused for removably securing a separate arc chute 50 to the stationaryunit 11 in association with each of the contacts 31. The bolts 52 areanchored in a horizontally-extending strip 53 of insulating materialthat in turn is rigidly fastened to the front sides of the respectivemembers 34 of the stationary contacts 31. Since neither the presence ofthe arc chutes 50, their design particulars, nor the method of mountingthe chutes on the stationary unit 11 are material to the presentinvention, a detailed description of these parts will be omitted.

The construction of the carriage 101 of the switch will now bedescribed. It comprises a metal front frame having generally L-shapedside structures that are rigidly fastened together by a plurality ofcross pieces. Each of the side structures of this frame comprises anangle forming a vertical front corner post 102, a side plate 103 affixedto the post 102 near its lower end and extending rearwardly therefrom,and a diagonal brace 104 interconnecting the rear of plate 103 and theupper end of post 102. A shaft 105 extends horizontally across thebottom of the carriage and is journalled at its opposite ends to therespective side plates 103, and two rigid cross members 106 and 107 spanthe corner posts 102 to complete the frame. The escutcheon 110 is boltedat 111 to the cross members 106 and 107 of the front frame as shown.This frame, in combination with a switch member 203 that is movablysupported thereby and a mechanism for moving the same, comprises aportable unit that, in

accordance with my invention, is separably hinged to the stationary unit11 for angular movement between two different positions.

For the purpose of separably hinging the portable unit on the stationaryunit, a coaxial pair of laterally projecting support pins 116 arerespectively located on the opposite side plates 103 of the carriage 101in the vicinity of the front side thereof. These pins fit into theaforesaid notches 16 in the upstanding plates 14 of the stationaryframe, and the carriage 101 can pivot or swing about the common axis ofthese pins to and away from a predetermined first or operating positionin which it is shown in FIGS. 1, 2, and 5. This position is determinedby the anchor pin 18b abutting the top edge of a slot 118 formed in thebottom of each side plate 103 of the carriage as shown. So lon as thecarriage 101 is in the operating position, the upper lip 14a of eachnotch 16 overhangs another pin 117 located next to each support pin 116(see FIGS. 1 and 2) to prevent lifting the portable unit vertically withrespect to the stationary unit 11.

From its first position the portable unit can be pivoted on its supportpins 116 through an angle of about 75 or degrees to a second or tiltedposition shown in FIG. 6, which position is determined by an appendage102a on each of the corner posts 102 abutting the under side of a stoppin 15a that is affixed to each of the diagonal braces 15 of thestationary unit. From its tilted position the portable unit can beseparated from the stationary unit for installation and servicingconvenience by manually lifting it so that the pins 116 leave thenotches 16, for which purpose a C-shaped carrying handle 103 isprominently located on the upper cross member 106 of the carriage 101.

The portable unit includes the switch member 203 which is adapted tosupport the aforesaid bridge-like electroconductive elements 201. Inaccordance with my in vention, the switch member 203 is pivotallymounted on the side plates 103 of the carriage 101 for reciprocalmovement relative thereto between predetermined closed and openpositions. The switch member is a channel of rigid insulating materialextending horizontally across the carriage between a pair of attachedmetal brackets or legs 204 that are supported by a coaxially pair ofpivot pins 119 projecting laterally from the respective side plates 103in the vicinity of the back side of the carriage. With the portable unitin its aforesaid first position, the pivot pins 119 are about coaxialwith the lower rotatable shaft 60 of the previously described contactclamping means. The axes of the pivot pins 119, the support pins 116,and the shaft are all oriented parallel to each other.

The electroconductive element 201 supported by the switch member 203 isshown in FIG. 2 as a cartridge fuse having vertically orientedblade-like terminals that comprise the aforesaid main contacts 201a and201b, respectively. Three separate fuses are removably supported by theswitch member in side-by-side electrically insulated relation to eachother, each fuse being located adjacent to the back side of the carriagewith its terminals aligned with a corresponding pair of relativelystationary jawlike contacts 31 and 41. Toward this end the member 203 isprovided with a plurality of spaced-apart pairs of fuse holders 205 and206 arranged to hold opposite terminals 201a and 201b of the respectivefuses 201. The preferred construction of these fuse terminal holders isbest seen in FIG. 4.

Each of the lower fuse terminal holders 206 is in the form of agenerally rectangular collar 206a projecting rearwardly from the bottomof the switch member 203, to which it is afiixed, and a relatively thin'U-shaped bracket 2061) subtending the collar. The blade-like fuseterminal 20117 is loosely embraced by the collar 20611, which restrictslateral movement of the blade, and it is supported by the interiorsurfaces of the bracket 2061) which limit edgewise movement thereof. Thebracket 206b is made thinner than the blade 201b so as to avoidinterfering with the direct electrical connection between the blade andthe jaw-like contact 41. The hook-like protrusion 2060 shown at thebottom of the holder 206 will extend behind one of the tubular bolts 62on the lower rotatable drive shaft 60 of the contact clamping meanswhenever the portable carriage 101 is in its aforesaid operatingposition.

Each of the upper fuse terminal holders 205 is in the form of aninverted L-shaped metal member that comprises the aforesaid arcingcontact 202. This contact has one end 202a pivotally attached to anupright bracket 207 that is affixed to the top of the switch member 203,and its other end is integrally connected to a pair of parallel,spaced-apart arms 205a. A threaded bolt 208 attached to the free end ofeach of the arms 205a is normally secured in a cooperating nut 209affixed to the switch member 203, thereby releasably fastening thecontact 202 to the switch member. The arms 205a loosely embrace theblade-like fuse terminal 201a and hence restrict lateral movement of theblade. The side 202b of contact 202 adjoining the arms 205a is adaptedto abut the leading edge of the blade 201a as shown, and contactpressure is there maintained by a spring-loaded plunger 210 that urgesthe blade away from the switch member 203. The arcing contact 202 ismade thinner than the blade 201a so as to avoid interfering with adirect electrical connection between the blade and the main jawlikecontact 31.

By unfastening the arms 205a from the switch member 203, the upper fuseterminal holder 205 can be pivoted about 202a from a normal position(shown in solid lines in FIG. 4) to another position (shown in brokenlines) wherein the arcing contact 202 is disengaged from the blade 201a,whereby the fuse 201 is released from the switch member for removal andreplacement purposes. This operation is most conveniently accomplishedwhile the carriage 101 is in its tilted position described hereinbefore.

The switch member 203 of the portable unit is moved between its open andclosed positions by an operating mechanism that will next be described.The operating mechanism in its preferred form includes the manualoperating handle 120. As can be seen in FIGS. 1 and 2, handle 120depends radially from the front end of a short horizontal shaft 121 towhich it is affixed. The shaft 121 extends through the escutcheon 110and is journaled near its rear end in a bearing 122 that is centrallysupported by the upper cross member 106 of the carriage 101. Aplate-like crank 123 is keyed to the rear end of the shaft 121. V

The plate 123 is drivingly connected to the rotatable shaft 105 of theswitch operating mechanism by means of a tie rod 124. A pin 123aprotruding rearwardly from the plate 123 is loosely embraced by aneyelet formed at the upper end of the tie rod 124. The lower end of thisrod is pivotally attached to a pin 125a spanning a yoke 125 that ispivotally supported at the distal end of an arm 126 projecting radiallyfrom a central portion of the shaft 105 to which it is rigidly anchored,whereby a universal joint is formed between the tie rod 124 and the arm126. With this arrangement, the shaft 105 is rotated approximately 45degrees in a clockwise direction (as viewed from the right sideof theswitch) in response to the operating handle 120 being pivotedcounterclockwise (front view) about the axis of the shaft 121 from itsvertical position shownin FIGS. 1 and 2 through an angle ofapproximately 135 degrees to its fully raised position. If desired, theshaft 105 could alternatively be driven by other suitable means, such asa stored energy spring-actuated mechanism.

It is desirable to releasably lock the manual operating handle 120 ineach of its vertical and raised positions, for which purpose a springloaded plunger 112 is mounted on the upper cross member 106 behind theescutcheon 110. Whenever the handle is in its vertical (open) position,which position is defined by a first shoulder 123b of the plate 123engaging a boss 106a on the cross member 106, the plunger 112 isspring-biased rearwardly into a cooperating notch 123a provided in theedge of plate 123, whereby counterclockwise movement of the plate isblocked until the plunger is withdrawn by pulling a knob 113 that isattached thereto. The knob 113 is accessible from the front side of theescutcheon 110. When the knob is pulled and counterclockwise movement ofthe operating handle 120 is begun, the front surface of the plate 123slides across the end of the plunger 112. As the handle reaches itsfully (closed) position, which position is defined by an opposingshoulder 123d of the plate 123 engaging the same boss 106a, the firstshoulder 123:5 will move just beyond the plunger 112 which is then freeto move rearwardly into a blocking position therewith, whereby reversemovement of the handle 120 in a clockwise direction is physicallyprevented until plate 123 is again released by manually pulling the knob113.

The driven shaft 105, as was mentioned hereinbefore, extendshorizontally across the carriage 101 and is journaled at its oppositeends to the respective side plates 103. A pair of cam members 127 arekeyed to the shaft 105 near its respective ends. The preferredconfiguration of each cam member 127 is best seen in FIG. 2. Each isprovided with a cam slot 128 having a generally vertical section 128athat intersects and extends downwardly from the rear end of a generallyhorizontal section 12812. A roller 204a is disposed in the cam slot 128.The roller 204a is mounted on the supporting leg 204 of the movableswitch member 203, and it traverses the cam slot 128 during closing andopening operations of the switch operating mechanism.

The action of the mechanism during a closing operation will now beconsidered.

The switch closing operation is accomplished in tWo distinct steps. Thefirst step is carried out by releasing and angularly moving the manualoperating handle through about one-half of its -degree counterclockwiseclosing stroke. This will cause the arm 126 on the shaft 105 to movethrough approximately three-fifths of its 45-degree throw, therebyrotating the shaft 105 and its cam members 127 a corresponding amount.During this step the front edge of the first section 128a of the camslot 128 moves rearwardly and cams the roller 204a upwardly with respectthereto. As a result, the rollers 204a, the legs 204, and hence theswitch member 203 are driven clockwise on the pivot pins 119 along anapproximately 42-degree arcuate course from the initial open positionshown in FIG. 2 to the closed position in which these parts are shown inFIG. 5. This clockwise movement of the switch member 203 carries theblade-like upper terminals 201a of the respective cartridge fuses 201into wiping engagement with the associated jaw-like stationary contacts31.

For the remainder of the closing operation, the roller 204a will be inthe second cam slot section 1281; whose bottom edge closely conforms tothe arc of a circle concentric with the shaft 105, whereby the movableswitch member 203 is held in its closed position but no furtherclockwise angular motion is imparted thereto.

With the fuse-carrying switch member 203 in its closed position, andwith the carriage 101 fixed in its operating position shown in FIG. 5,the terminals at the opposite ends of each cartridge fuse 201 directlyengage both of the main stationary contacts 31 and 41 that areassociated therewith, thereby making or completing a fused electriccircuit between corresponding upper and lower conductors 30 and 40. Forthe purpose of positively anchoring the portable carriage 101 in itsaforesaid disposition to the stationary unit 11 while the switch isbeing closed, each cam member 127 has been provided with a lobe 127aWhose leading edge engages a roller 10c mounted on the adjacentsupporting locking member 18 so as to tilt this member counterclockwiseupon initial clockwise rotation of the cam member 127. When so tilted,the anchor pin 18b carried by the member 18 shifts frontwardly from themouth to an interior portion of the notch 118 that is formed in thebottom edge of the side plate 103 of the carriage 101. The carriage 101is then locked to the stationary unit 11, and it cannot be movedrelative thereto until the side plate 103 is subsequently released byegress of the pin 1812 from the notch 118 when the cam member 127returns to its original position. This prevents the hazardouspossibility of opening the switch contacts by tilting the carriage.

The second step of the switch closing operation is used to actuate theabove-described contact clamping means so as to apply high contactpressure on the then interengaging main contacts of the switch. Thisstep is carried out by continuing to move the manual operating handle120 through the remainder of its counterclockwise closing stroke to itsfully raised position, thereby causing the shaft 105 and its cam members127 to turn clockwise from the position shown in FIG. 5. If desired,spring means (not shown) could be coupled to the handle 120 so as toassist the operator in moving the handle during this part of its closingstroke.

With the cam member 127 in its FIG. position, a camming surface 129 onthe rear edge thereof engages a roller 260 mounted at one end of acoupling lever 261 whose opposite end 262 is slotted. The axle of theroller 260 protrudes a short distance in the direction of the lowerstationary contact 41 which is adjacent thereto. At a point midwaybetween the roller 260 and the slot 262, the lever 261 is journaled onthe pivot pin 119 which projects laterally from the side plate 103 ofthe carriage 101. A tension spring 263 (see FIG. 2) biases this lever ina counterclockwise sense to a normal position determined by a boss onthe lever engaging the side plate 103.

With the lever 261 in its normal position and with the carriage 101anchored in the fixed disposition shown in FIG. 5, the slot 262 willregister with a pin 66b protruding from the crank 66 that is keyed tothe adjacent end of the lower rotatable shaft 60 as previouslydescribed. (The lower shaft 60 is coaxial with the pivot pin 119.) Thecrank 66 is also provided with a slot 660 diametrically opposite the pin66b, which slot registers with the protruding axle of the roller 260.Thus the crank 66 is coupled so the lever 261 for joint rotationtherewith. The same coupling is provided at the far side of the switch.

As the second step of the switch closing operation is carried out, thecamming edge 129 of the member 127 advances in such a manner as to drivethe roller 260 and hence the lever 261 clockwise about the pivot pin 119through an angle of approximately 45 degrees. The crank 66, beingcoupled to the lever 261, is correspondingly rotated with respect to theaxis of the lower shaft 60, and the interconnected upper crank 65 isrotated conjointly therewith. As a result, each of the upper and lowerdrive shafts 60 of the contact clamping means is turned clockwise aboutits axis from the initial angular position in which it is shown in FIGS.2, 3, and 5 to a predetermined final angular position spaced from theinitial position by approximately 45 degrees. During the course of thisturning each tubular bolt 62 is screwed into the associated nut 63,thereby reducing the spacing between the bolt head and the nut andcompressing the interposed contact members 32, 33 and 201a (or 2011)).This contact clamping action is more fully explained above in connectionwith the description of FIG. 3.

The second step of the switch closing operation is completed when themanual operating handle 120 reaches its fully raised position (shown inbroken lines in FIGS. 1 and 5) where it is retained by the releasablelocking means 112, 113 previously described. Brief considera tion willnow be given to a switch opening operation,

10 which is essentially the reverse of the closing operation justdescribed.

The switch opening operation is begun by releasing the operating handle120 and angularly moving it in a clockwise direction (front view),thereby causing counterclockwise rotation (as viewed in FIG. 5) of theshaft and. its cam members 127. The illustrated cam member 127 isprovided with a hook-like part opposing the camming edge 129, and acamming edge 129a on this part pulls the roller 260 and hence the lever261 and the crank 66 in a counterclockwise direction. This action, whichis aided by the springs 67 and 263, simultaneously turns both of thedrive shafts 60 of the contact clamping means in a counterclockwise,pressure relieving direction. As the rear end of the second cam slotsection 12812 in the member 127 approaches the roller 204a, the couplinglever 261 returns to its normal position shown in FIG. 5 and each driveshaft 60 isreturned to its initial angular position, whereby thebolted-pressure connections between stationary contacts 31, 41 and fuseterminals 201a, 20112 are loosened before the movable switch member 203is moved away from its closed position.

Continued counterclockwise rotation of the cam member 127 after the rearedge of its first cam slot section 128a makes contact with the roller204a will cam the roller downwardly with respect thereto. As a result,the switch member 203 and supporting legs 204 are moved counterclockwiseon the pivot pins 119 along their predetermined arcuate course fromclosed to open positions. This reverse movement of the switch member 203effects separation of the upper fuse terminal 201a and its associatedarcing contact 202 from the stationary contact 31, and consequently theelectric circuit between the corresponding upper and lower conductors 30and 40 is opened.

The switch opening operation is completed when the manual operatinghandle reaches a vertical position (FIG. 2) where it is again retainedby the releasable locking means 112, 113.

The movable switch member 203 has been equipped with means for ensuringirreversible motion between its open and closed positions. This means,which is independent of the switch operating mechanism previouslydescribed, preferably comprises at each side of the switch an elongatedelement 250 aifixed to the switch member 203 and a tiltable lockingelement pivotally attached to the front corner post 102 of the frame ofthe carriage 101. As is apparent in FIGS. 2 and 5, the elongated element250 is part of the switch member supporting leg 204, and itslongitudinal centerline is oriented generally parallel to the arcuatecourse of movement of the switch member. The locking element 150 has apair of spaced-apart transverse pins 151 and 152 in frictionalengagement with opposite sides of the element 250. A bidirectionallyeffective torsion spring 153 encircles a boss 154 on the diagonal brace104 of the carriage frame and yieldably bears against a pin 155protruding laterally from the element 150, the direction of this biasbeing controlled by the position of a cooperating bar 156 pivotallymounted on the boss 154.

While the switch member 203 is being moved in its clockwise,switch-closing direction between a predetermined first position beforethe movable arcing contact 202 has engaged the relatively stationaryarcing contact 42 and a predetermined second position after main contactengagement takes place, the bar 156 is held by a curved surface 20411 ofthe leg 204 in a nearly horizontal position (see FIG. 5) that results inthe spring 153 depressing the locking element 150 and maintaining it insuch a tilted disposition on the elongated element 250 that clockwisemovement of the switch member is accompanied by unimpeded relativemotion of the element 250 and the pins 151, 152, whereas any attemptedreverse movement of the switch member causes the element 250 and thepins 151, 152 to bind and thereby to physically lock the switch memberbefore it can move appreciably in the reverse direction. Thisnon-reversing mechanism is thus effective during a switch-closingoperation to prevent separation of the cooperating contacts 202 and 42once engaged before the movable switch member 203 reaches the aforesaidsecond position. Consequently the switch cannot blow open if initiallyclosed on a severely short-circuited external electric power circuit,and the high forces of reaction associated with such a closing are nottransmitted to the manual operating handle 120.

As the switch member 203 moves into its closed position (FIG. adepending portion 250a of the elongated element 250 lifts the lockingelement 150 out of its tilted disposition to another disposition thatwill enable the elongated element to slide between the pins 151 and 152without binding on reverse movement thereof. During subsequentcounterclockwise movement of the switch member 203 toward its openposition, the bar 156 is pivoted clockwise and is held by the legsurface 204a in a nearly vertical position that results in the spring153 maintaining the locking element 150- in its lifted disposition,whereby the elements 250 and 150 are effective to prevent anyappreciable movement of the switch member in the clockwise directionuntil this member approaches the aforesaid first position. In responseto the switch member returning to its open position (FIG. 2), thelocking element 150 is tilted against the force of the bias spring 153to its original disposition in which the elongated element 250 is againable, without binding, to slide between the pins 151 and 152 onclockwise movement of the switch member 203.

As the movable switch member 203 is returning to its open position nearthe end of the switch-opening operation, the lobe 12711 on the cammember 127 moves beyond the roller 180 on the support and locking member18, and the rear edge of the lobe will engage and move alaterally-protruding pin 18d on the member 18. This tilts the wholemember 18 clockwise to a position in which the anchor pin 18b registerswith the mouth of the notch 118 in the side plate 103 of the carriage101, thereby disabling the anchoring means and releasing the carriage101 for angular movement on its support pins 116 from the operatingposition shown in FIG. 2 to the tilted position mentioned hereinbefore.

In FIG. 6 the portable unit of the opened switch is shown after havingbeen moved, relative to the stationary unit 11, to its tilted position.Such movement is elfected simply by pulling manually the carrying handle108 of the carriage 101 until the carriage is propelled by its ownweight counterclockwise about the axis of its support pins 116. It willbe apparent that during this swinging movement of the carriage 101 theaxle of roller 260 and the slot 262 at opposite ends of each couplinglever 261 separate, respectively, from the diametrically opposed slot66c and pin 66b of the associated crank 66. The tilted position of thecarriage 101 is reached when the appendage 102a on each of the frontcorner posts 102 of the carriage frame engages the under side of thecooperating stop pin 15a on each diagonal brace 15 of the stationaryunit 11.

In accordance with my invention, the support pins 116 are so locatedthat the above-described movement of the carriage 101 carries the lowerfuse terminals 2011) out of engagement with the stationary contacts 41,whereby each cartridge fuse 201 is completely separated from theassociated stationary contacts 31 and 41 of the switch. In the tiltedposition of the carriage 101, as is best seen in FIG. 6, each fuse hasboth of its terminals disconnected and deenergized, and it is exposedfor safe and convenient removal from the fuse terminal holders 205 and206. An operator can easily replace a blown fuse without danger oftouching an energized (live) stationary contact of the switch. Toimprove accessibility and 'hence to expedite the unfastening anddisengagement of the upper fuse terminal holder 205, the fuse-supportingswitch member can first be moved, relative to the carriage 101, in aclockwise direction on the pivot pins119 to its closed position byturning the manual operating handle 120 through its closing stroke. Inorder to ensure that the portable carriage 101 cannot then be moved fromits tilted position to its operating position (FIG. 5), each cam member127 has been provided wi'h a boss 127k that will not pass alaterally-displaced edge 15b of the stationary diagonal brace 15 untilthe cam member 127 is returned to its original angular position bycompleting the opening stroke of the handle 120.

While a preferred form of my invention has now been shown and describedby way of illustration, many modifications will occur to those skilledin the art. The claims which conclude this specification are thereforeintended to cover all such modifications as fall within the true spiritand scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A switch comprising:

(a) a first unit including means for removably supporting a bridge-likeelectroconductive element and additional means for movably mounting thesupporting means on the first unit;

(b) a second unit having a relatively stationary pair of spaced-apartelectric contacts;

(0) means for pivotally mounting said first unit on said second unit forreciprocal movement relative to the second unit to and away from a firstposition in which said element is adapted directly to engage and henceelectrically to interconnect both of said contacts;

((1) anchoring means for locking said first unit in its first positionto said second unit;

(e) means for so moving said supporting means relative to said firstunit while in said first position that said element disengages at leastone of said contacts; and

(f) means responsive to said movement of said supporting means fordisabling said anchoring means, thereby releasing said first unit forangular movement relative to the second unit to a second position inwhich said element is completely separated from both of said contactsand is exposed for safe and convenient removal from said supportingmeans.

2. The switch of claim 1 in which said bridge-like electroconductiveelement comprises a cartridge fuse.

3. In combination:

(a) a portable unit including means for removably supporting a cartridgefuse, the supporting means being mounted on the portable unit forangular movement relative thereto between predetermined closed and openpositions;

(b) a relatively stationary unit having a pair of spacedapart electriccontacts;

(c) means separably hinging said portable unit to said stationary unitfor angular movement between predetermined first and second positions,the supported fuse directly engaging and hence electricallyinterconnecting both of said contacts when the portable unit is in saidfirst position and said supporting means is in said closed position, andthe supported fuse being completely separated from both contacts andbeing exposed for safe and convenient removal from the supporting meanswhenever the portable unit is in said second position; and

( d) means for preventing movement of the portable unit from its firstto its second positions whenever the supporting means is in said closedposition.

4. The combination of claim 3 in which means is provided for preventingmovement of the portable unit from second to first positions when thefuse supporting means is in its closed position.

5. In combination:

(a) a carriage having a front side and a back side and means adaptedremovably to support a cartridge fuse on the carriage adjacent to theback side thereof, said supporting means being movably mounted on saidcarriage;

(b) a relatively stationary frame and a pair of spacedapart electriccontacts mounted on the frame,

() means for hinging said carriage to said frame for angular movementrelative to the frame between a first position in which the fuse isadapted to engage and 'hence to interconnect both of said contacts and asecond position in which the fuse is disposed for safe and convenientremoval from said supporting means;

(d) switching means operative from the front side of said carriage forso moving said supporting means while the carriage is in said firstposition that the fuse disengages at least one of said contacts; and

(e) interlocking means on the frame for preventing movement of saidcarriage away from its first position so long as the fuse is engagingboth of said contacts and for permitting such movement of the carriageafter an operation of said switching means.

6. The combination of claim in which the supporting means is pivotallymounted on the carriage for angular movement relative thereto about afirst axis located in the vicinity of the back side thereof, and inwhich the carriage is hinged to the frame for swinging between its firstand second positions about a second axis parallel to said first axis andlocated in the vicinity of the front side of the carriage.

7. In combination:

(a) a portable carriage having a front side and a back side and meansadapted removably to support a cartridge fuse adjacent to the back sideof the carriage, said supporting means being mounted on said carriagefor angular movement relative thereto:

(b) a relatively stationary frame and a pair of spacedapart electriccontacts mounted on the frame;

(c) means for pivotally mounting said carriage on said frame so that thecarriage is angularly movable to and away from a predetermined position,said mounting means including anchoring means for releasably locking thecarriage in said predetermined position to the frame;

5 (d) a mechanism connected to said supporting means and operative fromthe front side of said carriage while in said predetermined position tomove the supporting means so as to carry the supported fusealternatively into engagement with both of said contacts and out ofengagement with at least one of said contacts; and

(e) means effective when the supported fuse has been carried out ofengagement with at least one of said contacts for disabling saidanchoring means, thereby releasing said carriage for angular motion fromsaid predetermined position to a diiferent position in which the fuse iscompletely separated from both of said contacts and is exposed for safeand convenient removal from said supportnig means.

8. The combination of claim 7 in which the supporting means is adaptedremovably to support three separate cartridge fuses and in which threeseparate pairs of spaced-apart electric contacts are mounted on theframe for engagement respectively by said fuses upon operation of themechanism.

References Cited by the Examiner UNITED STATES PATENTS 2,504,876 4/1950Pringle 20050 2,982,827 5/1961 Goetz 200-50 3,213,221 10/1965 McMillenet a1 200-50 References Cited by the Applicant UNITED STATES PATENTS1,519,044 12/1924 Paiste.

ROBERT K. SCHAEFER, Primary Examiner. .T. R. SCOTT, Assistant Examiner.

1. A SWITCH COMPRISING: (A) A FIRST UNIT INCLUDING MEANS FOR REMOVABLYSUPPORTING A BRIDGE-LIKE ELECTOCONDUCTIVE ELEMENT AND ADDITIONAL MEANSFOR MOVABLY MOUNTING THE SUPPORTING MEANS ON THE FIRST UNIT; (B) ASECOND UNIT HAVING A RELATIVELY STATIONARY PAIR OF SPACED-APART ELECTRICCONTACTS; (C) MEANS FOR PIVOTALLY MOUNTING SAID FIRST UNIT ON SAIDSECOND UNIT FOR RECIPROCAL MOVEMENT RELATIVE TO THE SECOND UNIT TO ANDAWAY FROM A FIRST POSITON IN WHICH SAID ELEMENT IS ADAPTED DIRECTLY TOENGAGE AND HENCE ELECTRICALLY TO INTERCONNECT BOTH OF SAID CONTACTS; (D)ANCHORING MEANS FOR LOCKING SAID FIRST UNIT IN ITS FIRST POSITION TOSAID SECOND UNIT; (E) MEANS FOR SO MOVING SAID SUPPORTING MEANS RELATIVETO SAID FIRST UNIT WHILE IN SAID FIRST POSITION THAT SAID ELEMENTDISENGAGES AT LEAST ONE OF SAID CONTACTS; AND (F) MEANS RESPONSIVE TOSAID MOVEMENT OF SAID SUPPORTING MEANS FOR DISABLING SAID ANCHORINGMEANS, THEREBY RELEASING SAID FIRST UNIT FOR ANGULAR MOVEMENT RELATIVETO THE SECOND UNIT TO A SECOND POSITION IN WHICH SAID ELEMENT ISCOMPLETELY SEPARATED FROM BOTH OF SAID CONTACTS AND IS EXPOSED FOR SAFEAND CONVENIENT REMOVAL FROM SAID SUPPORTING MEANS.